def check_leaf(self):
""" Leaf validity rules:
- a valid leaf is an operator or a leaf
- a valid leaf has a field objects unless
- it is not a tuple
- it is an inherited field
- left is id, operator is 'child_of'
- left is in MAGIC_COLUMNS
"""
if not is_operator(self.leaf) and not is_leaf(self.leaf, True):
raise ValueError("Invalid leaf %s" % str(self.leaf))
def is_operator(self):
return is_operator(self.leaf)