Test for cmp nodes

tests/run/cmp.pyx

+__doc__ = """
+    >>> single_py(1, 2)
+    True
+    >>> single_py(2, 1)
+    False
+    >>> cascaded_py(1, 2, 3)
+    True
+    >>> cascaded_py(1, 2, -1)
+    False
+    >>> cascaded_py(10, 2, 3)
+    False
+
+    >>> single_c(1, 2)
+    True
+    >>> single_c(2, 1)
+    False
+    >>> cascaded_c(1, 2, 3)
+    True
+    >>> cascaded_c(1, 2, -1)
+    False
+    >>> cascaded_c(10, 2, 3)
+    False
+"""
+
+def single_py(a, b):
+    return a < b
+
+def cascaded_py(a, b, c):
+    return a < b < c
+
+def single_c(int a, int b):
+    return a < b
+
+def cascaded_c(double a, double b, double c):
+    return a < b < c