def find_matching_function(self, name, param_count, must_return):
"""Finds and returns the function definition which
matches with the given 'name' and parameter count.
If 'must_return' is True, then the function must also
return some value to be valid
"""
f = self.functions.get(Function.mangle(name, param_count))
if f and (not must_return or f.returns is not None):
return f
return None
