Added Identity function

shublang/shublang.py

@@ -130,7 +130,7 @@ def decode(iterable, encoding):
 @Pipe
 def find(iterable, sub, start=None, end=None):
     """Returns the lowest index in the string where the sub is found.
-    If specified, the start and end params serve to slice the string 
+    If specified, the start and end params serve to slice the string
     where sub should be searched.
 
     :param iterable: collection of data to transform
@@ -332,6 +332,11 @@ def extract_currency(iterable):
 def urljoin(iterable, base):
     return (parse.urljoin(base, url) for url in iterable)
 
+@Pipe
+def identity(iterable, element):
+    """ Return the same element is passed as parameter."""
+    return element
+
 
 filter = where
 map = select

tests/test_functions.py

@@ -400,3 +400,27 @@ def test_join(test_input, expected):
 )
 def test_urljoin(test_input, expected):
     assert evaluate(*test_input) == expected
+
+@pytest.mark.parametrize(
+    "test_input,expected",
+    [
+        (
+            ['identity(True)',
+             [10, 'far', ['boo', 3]]],
+                True,
+        ),
+        (
+            ['identity("InStock")',
+             ["In Stock.", "Only 3 in Stock", "Stock Ok"]],
+            "InStock",
+        ),
+        (
+            ['identity((1,2,3,4,5))',
+             "foo"],
+            (1,2,3,4,5),
+        ),
+    ]
+)
+
+def test_identity(test_input, expected):
+    assert evaluate(*test_input) == expected