code: def signed_pow_fcn(y):
      return lambda x: signed_pow(x, y)
  
imports: import math
  from datetime import datetime
  from datetime import timedelta
  import numpy
  import pandas
  import pytz
  from holidays_ext import get_holidays
  from pandas.tseries.frequencies import to_offset
  from scipy.special import expit
  from greykite.common import constants
  from greykite.common.python_utils import split_offset_str
label_desc: Use image node_id 30 for calling a global function with example usage: signed_pow_fcn(y) and returns: function