trepan/lib/display.py
def signature(frame):
    '''return suitable frame signature to key display expressions off of.'''
    if not frame: return None
    code = frame.f_code
    return (code.co_name, code.co_filename, code.co_firstlineno)
def signature(frame):
    '''return suitable frame signature to key display expressions off of.'''
    if not frame: return None
    code = frame.f_code
    return (code.co_name, code.co_filename, code.co_firstlineno)
return suitable frame signature to key display expressions off of.