Start Operators with no meaning section (#1171)

The Star function is  needed for Rubi.

Author: rocky

mathics/builtin/no_meaning.py

@@ -0,0 +1,42 @@
+# -*- coding: utf-8 -*-
+# Note: this will be redone soon to pull no-meaning operator information from operators.yml out
+# of the MathicsScanner project.
+"""
+Operators without Built-in Meanings
+
+Not all operators recognized by the Mathics3 are associated with functions that have built‐in meanings.
+You can use these operators as a way to build up your own notation within the Mathics3.
+"""
+
+from mathics.core.attributes import A_NO_ATTRIBUTES
+from mathics.core.builtin import BinaryOperator
+
+
+class Star(BinaryOperator):
+    r"""
+    Star <url>
+    :WML link:
+    https://reference.wolfram.com/language/ref/Star.html</url>
+
+    <dl>
+      <dt>'Star[$x$, $y$, ...]'
+      <dd>displays $x$ ⋆ $y$ ⋆ ...
+    </dl>
+
+    >> Star[x, y, z]
+     = x ⋆ y ⋆ z
+
+    >> a \[Star] b
+     = a ⋆ b
+    """
+
+    attributes = A_NO_ATTRIBUTES
+    default_formats = False  # Don't use any default format rules. Instead, see below.
+    formats = {
+        (("InputForm", "OutputForm", "StandardForm"), "Star[args__]"): (
+            'Infix[{args}, "⋆"]'
+        ),
+    }
+
+    operator = "⋆"  # \u22C6
+    summary_text = "star symbol"

mathics/core/builtin.py

@@ -1133,9 +1133,11 @@ def __init__(self, *args, **kwargs):
 
 class BinaryOperator(Operator):
     """
-    Class for Builtin Binary Operators, e.g. Plus (+)
+    Class for Builtin Infix Operators (which includes Binary
+    operators), e.g. Plus (+).
     """
 
+    # Note: grouping must be Python string, not a Symbol.
     grouping = "System`None"  # NonAssociative, None, Left, Right
 
     def __init__(self, *args, **kwargs):