def genHalfAndHalf(pset, min_, max_, type_=None):
 method = random.choice((genGrow, genFull))
 return method(pset, min_, max_, type_)

def genHalfAndHalf ( pset , min_ , max_ , type_ = None ) : method = random . choice ( ( genGrow , genFull ) ) return method ( pset , min_ , max_ , type_ )
generate an expression with a primitiveset *pset* .