def str_startswith(arr, pat, na=np.nan):
 f = (lambda x: x.startswith(pat))
 return _na_map(f, arr, na, dtype=bool)

def str_startswith ( arr , pat , na = np . nan ) : f = ( lambda x : x . startswith ( pat ) ) return _na_map ( f , arr , na , dtype = bool )
return boolean series/array indicating whether each string in the series/index starts with passed pattern .