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SteveL-MSFTSteveL-MSFT
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Merge pull request #1126 from Gijsreyn/mcp-list-extension
Add `list_dsc_function()` tool to MCP server
2 parents 95a5241 + a844e10 commit 47b15d6

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‎dsc/locales/en-us.toml‎

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@@ -66,6 +66,9 @@ serverStopped = "MCP server stopped"
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failedToCreateRuntime = "Failed to create async runtime: %{error}"
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serverWaitFailed = "Failed to wait for MCP server: %{error}"
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[mcp.list_dsc_functions]
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invalidNamePattern = "Invalid function name pattern '%{pattern}'"
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[mcp.list_dsc_resources]
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resourceNotAdapter = "The resource '%{adapter}' is not a valid adapter"
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adapterNotFound = "Adapter '%{adapter}' not found"

‎dsc/src/mcp/list_dsc_functions.rs‎

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@@ -0,0 +1,62 @@
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// Copyright (c) Microsoft Corporation.
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// Licensed under the MIT License.
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use crate::mcp::mcp_server::McpServer;
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use dsc_lib::functions::{FunctionDispatcher, FunctionDefinition};
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use dsc_lib::util::convert_wildcard_to_regex;
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use rmcp::{ErrorData as McpError, Json, tool, tool_router, handler::server::wrapper::Parameters};
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use rust_i18n::t;
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use schemars::JsonSchema;
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use serde::{Deserialize, Serialize};
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use regex::RegexBuilder;
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use tokio::task;
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#[derive(Serialize, JsonSchema)]
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pub struct FunctionListResult {
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pub functions: Vec<FunctionDefinition>,
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}
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#[derive(Deserialize, JsonSchema)]
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pub struct ListFunctionsRequest {
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#[schemars(description = "Optional function name to filter the list. Supports wildcard patterns (*, ?)")]
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pub function_filter: Option<String>,
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}
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#[tool_router(router = list_dsc_functions_router, vis = "pub")]
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impl McpServer {
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#[tool(
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description = "List available DSC functions to be used in expressions with optional filtering by name pattern",
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annotations(
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title = "Enumerate all available DSC functions on the local machine returning name, category, description, and metadata.",
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read_only_hint = true,
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destructive_hint = false,
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idempotent_hint = true,
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open_world_hint = true,
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)
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)]
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pub async fn list_dsc_functions(&self, Parameters(ListFunctionsRequest { function_filter }): Parameters<ListFunctionsRequest>) -> Result<Json<FunctionListResult>, McpError> {
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let result = task::spawn_blocking(move || {
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let function_dispatcher = FunctionDispatcher::new();
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let mut functions = function_dispatcher.list();
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// apply filtering if function_filter is provided
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if let Some(name_pattern) = function_filter {
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let regex_str = convert_wildcard_to_regex(&name_pattern);
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let mut regex_builder = RegexBuilder::new(&regex_str);
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regex_builder.case_insensitive(true);
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let regex = regex_builder.build()
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.map_err(|_| McpError::invalid_params(
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t!("mcp.list_dsc_functions.invalidNamePattern", pattern = name_pattern),
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None
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))?;
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functions.retain(|func| regex.is_match(&func.name));
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}
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Ok(FunctionListResult { functions })
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}).await.map_err(|e| McpError::internal_error(e.to_string(), None))??;
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Ok(Json(result))
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}
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}

‎dsc/src/mcp/mcp_server.rs‎

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@@ -20,7 +20,7 @@ impl McpServer {
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#[must_use]
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pub fn new() -> Self {
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Self {
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tool_router: Self::list_dsc_resources_router() + Self::show_dsc_resource_router(),
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tool_router: Self::list_dsc_resources_router() + Self::show_dsc_resource_router() + Self::list_dsc_functions_router(),
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}
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}
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}

‎dsc/src/mcp/mod.rs‎

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@@ -9,6 +9,7 @@ use rmcp::{
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};
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use rust_i18n::t;
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pub mod list_dsc_functions;
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pub mod list_dsc_resources;
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pub mod mcp_server;
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pub mod show_dsc_resource;

‎dsc/tests/dsc_mcp.tests.ps1‎

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@@ -6,6 +6,7 @@ Describe 'Tests for MCP server' {
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$processStartInfo = [System.Diagnostics.ProcessStartInfo]::new()
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$processStartInfo.FileName = "dsc"
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$processStartInfo.Arguments = "--trace-format plaintext mcp"
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$processStartInfo.UseShellExecute = $false
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$processStartInfo.RedirectStandardError = $true
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$processStartInfo.RedirectStandardOutput = $true
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$processStartInfo.RedirectStandardInput = $true
@@ -70,6 +71,7 @@ Describe 'Tests for MCP server' {
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}
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$tools = @{
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'list_dsc_functions' = $false
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'list_dsc_resources' = $false
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'show_dsc_resource' = $false
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}
@@ -207,4 +209,93 @@ Describe 'Tests for MCP server' {
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$response.error.code | Should -Be -32602
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$response.error.message | Should -Not -BeNullOrEmpty
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}
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It 'Calling list_dsc_functions works' {
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$mcpRequest = @{
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jsonrpc = "2.0"
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id = 8
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method = "tools/call"
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params = @{
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name = "list_dsc_functions"
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arguments = @{}
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}
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}
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$response = Send-McpRequest -request $mcpRequest
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$response.id | Should -Be 8
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$functions = dsc function list --output-format json | ConvertFrom-Json
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$response.result.structuredContent.functions.Count | Should -Be $functions.Count
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$mcpFunctions = $response.result.structuredContent.functions | Sort-Object name
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$dscFunctions = $functions | Sort-Object name
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for ($i = 0; $i -lt $dscFunctions.Count; $i++) {
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($mcpFunctions[$i].psobject.properties | Measure-Object).Count | Should -BeGreaterOrEqual 8
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$mcpFunctions[$i].name | Should -BeExactly $dscFunctions[$i].name -Because ($response.result.structuredContent | ConvertTo-Json -Depth 10 | Out-String)
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$mcpFunctions[$i].category | Should -BeExactly $dscFunctions[$i].category -Because ($response.result.structuredContent | ConvertTo-Json -Depth 10 | Out-String)
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$mcpFunctions[$i].description | Should -BeExactly $dscFunctions[$i].description -Because ($response.result.structuredContent | ConvertTo-Json -Depth 10 | Out-String)
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}
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}
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It 'Calling list_dsc_functions with function_filter filter works' {
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$mcpRequest = @{
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jsonrpc = "2.0"
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id = 9
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method = "tools/call"
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params = @{
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name = "list_dsc_functions"
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arguments = @{
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function_filter = "array"
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}
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}
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}
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$response = Send-McpRequest -request $mcpRequest
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$response.id | Should -Be 9
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$response.result.structuredContent.functions.Count | Should -Be 1
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$response.result.structuredContent.functions[0].name | Should -BeExactly "array"
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$response.result.structuredContent.functions[0].category | Should -BeExactly "Array"
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}
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It 'Calling list_dsc_functions with wildcard pattern works' {
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$mcpRequest = @{
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jsonrpc = "2.0"
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id = 10
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method = "tools/call"
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params = @{
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name = "list_dsc_functions"
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arguments = @{
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function_filter = "*Array*"
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}
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}
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}
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$response = Send-McpRequest -request $mcpRequest
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$response.id | Should -Be 10
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$arrayFunctions = dsc function list --output-format json | ConvertFrom-Json -Depth 20 | Where-Object { $_.name -like "*Array*" }
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$response.result.structuredContent.functions.Count | Should -Be $arrayFunctions.Count
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foreach ($func in $response.result.structuredContent.functions) {
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$func.name | Should -Match "Array" -Because "Function name should contain 'Array'"
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}
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}
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# dont check for error as dsc function list returns empty list for invalid patterns
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It 'Calling list_dsc_functions with invalid pattern returns empty result' {
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$mcpRequest = @{
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jsonrpc = "2.0"
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id = 11
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method = "tools/call"
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params = @{
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name = "list_dsc_functions"
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arguments = @{
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function_filter = "[invalid]"
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}
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}
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}
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$response = Send-McpRequest -request $mcpRequest
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$response.id | Should -Be 11
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$response.result.structuredContent.functions.Count | Should -Be 0
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$response.result.structuredContent.functions | Should -BeNullOrEmpty
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}
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}

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