Correct conversion from Python bytes & bytearrays (#1516)

A small misfeature/Bug noticed by bdlucas1 in implementing NumericArray.
Before the recent work on ByteArray, this was less wrong, but still a
little wrong.

Author: rocky

mathics/core/convert/python.py

@@ -7,7 +7,15 @@
 
 import numpy
 
-from mathics.core.atoms import Complex, Integer, NumericArray, Rational, Real, String
+from mathics.core.atoms import (
+    ByteArray,
+    Complex,
+    Integer,
+    NumericArray,
+    Rational,
+    Real,
+    String,
+)
 from mathics.core.number import get_type
 from mathics.core.symbols import (
     BaseElement,
@@ -16,7 +24,7 @@
     SymbolNull,
     SymbolTrue,
 )
-from mathics.core.systemsymbols import SymbolByteArray, SymbolRule
+from mathics.core.systemsymbols import SymbolRule
 
 
 def from_bool(arg: bool) -> BooleanType:
@@ -112,9 +120,7 @@ def from_python(arg: Any) -> BaseElement:
     elif isinstance(arg, list) or isinstance(arg, tuple):
         return to_mathics_list(*arg, elements_conversion_fn=from_python)
     elif isinstance(arg, bytearray) or isinstance(arg, bytes):
-        from mathics.builtin.binary.bytearray import ByteArray
-
-        return Expression(SymbolByteArray, ByteArray(arg))
+        return ByteArray(arg)
     elif isinstance(arg, numpy.ndarray):
         return NumericArray(arg)
     else:

test/core/convert/test_from_python.py

@@ -0,0 +1,12 @@
+from mathics.core.atoms import ByteArray
+from mathics.core.convert.python import from_python
+
+
+def test_from_python():
+    assert isinstance(
+        from_python(b"abc"), ByteArray
+    ), "Python bytes() converts to a Mathics3 ByteArray"
+    assert isinstance(
+        from_python(bytearray([1, 2, 3])), ByteArray
+    ), "Python bytearray converts to a Mathics3 ByteArray"
+    # Many other tests are imagined to come...