code: def datetime_as_string(arr, unit=None, timezone=None, casting=None):
      """
      datetime_as_string(arr, unit=None, timezone='naive', casting='same_kind')
  
      Convert an array of datetimes into an array of strings.
  
      Parameters
      ----------
      arr : array_like of datetime64
          The array of UTC timestamps to format.
      unit : str
          One of None, 'auto', or
          a :ref:`datetime unit <arrays.dtypes.dateunits>`.
      timezone : {'naive', 'UTC', 'local'} or tzinfo
          Timezone information to use when displaying the datetime. If 'UTC',
          end with a Z to indicate UTC time. If 'local', convert to the local
          timezone first, and suffix with a +-#### timezone offset. If a tzinfo
          object, then do as with 'local', but use the specified timezone.
      casting : {'no', 'equiv', 'safe', 'same_kind', 'unsafe'}
          Casting to allow when changing between datetime units.
  
      Returns
      -------
      str_arr : ndarray
          An array of strings the same shape as `arr`.
  
      Examples
      --------
      >>> import pytz
      >>> d = np.arange('2002-10-27T04:30', 4*60, 60, dtype='M8[m]')
      >>> d
      array(['2002-10-27T04:30', '2002-10-27T05:30', '2002-10-27T06:30',
             '2002-10-27T07:30'], dtype='datetime64[m]')
  
      Setting the timezone to UTC shows the same information, but with a Z suffix
  
      >>> np.datetime_as_string(d, timezone='UTC')
      array(['2002-10-27T04:30Z', '2002-10-27T05:30Z', '2002-10-27T06:30Z',
             '2002-10-27T07:30Z'], dtype='<U35')
  
      Note that we picked datetimes that cross a DST boundary. Passing in a
      ``pytz`` timezone object will print the appropriate offset
  
      >>> np.datetime_as_string(d, timezone=pytz.timezone('US/Eastern'))
      array(['2002-10-27T00:30-0400', '2002-10-27T01:30-0400',
             '2002-10-27T01:30-0500', '2002-10-27T02:30-0500'], dtype='<U39')
  
      Passing in a unit will change the precision
  
      >>> np.datetime_as_string(d, unit='h')
      array(['2002-10-27T04', '2002-10-27T05', '2002-10-27T06', '2002-10-27T07'],
            dtype='<U32')
      >>> np.datetime_as_string(d, unit='s')
      array(['2002-10-27T04:30:00', '2002-10-27T05:30:00', '2002-10-27T06:30:00',
             '2002-10-27T07:30:00'], dtype='<U38')
  
      'casting' can be used to specify whether precision can be changed
  
      >>> np.datetime_as_string(d, unit='h', casting='safe')
      Traceback (most recent call last):
          ...
      TypeError: Cannot create a datetime string as units 'h' from a NumPy
      datetime with units 'm' according to the rule 'safe'
      """
      return (arr,)
  
imports: import functools
  from .None import overrides
  from .None import _multiarray_umath
  from ._multiarray_umath import *
  from ._multiarray_umath import _flagdict, from_dlpack, _place, _reconstruct, _vec_string, _ARRAY_API, _monotonicity, _get_ndarray_c_version, _get_madvise_hugepage, _set_madvise_hugepage, _get_promotion_state, _set_promotion_state
label_desc: Use image node_id 23 for calling a global function with example usage: datetime_as_string(arr, unit, timezone, casting) and returns: arr