Add docstring

Author: blegat

src/ParameterJuMP.jl

@@ -234,6 +234,12 @@ function add_parameters(model::JuMP.Model, val::AbstractArray{R,N}) where {R,N}
     return out
 end
 
+"""
+    all_parameters(model::JuMP.AbstractModel)::Vector{ParameterRef}
+
+Returns a list of all parameters currently in the model. The parameters are
+ordered by creation time.
+"""
 function all_parameters(model::JuMP.AbstractModel)
     data = _getparamdata(model)
     return ParameterRef[ParameterRef(ind, model) for ind in data.inds]