code: def column_or_1d(y, warn=False):
      """Ravel column or 1d numpy array, else raises an error
      Parameters
      ----------
      y : array-like
      warn : boolean, default False
         To control display of warnings.
      Returns
      -------
      y : array
      """
      shape = np.shape(y)
      if len(shape) == 1:
          return np.ravel(y)
      if len(shape) == 2 and shape[1] == 1:
          if warn:
              warnings.warn(
                  "A column-vector y was passed when a 1d array was"
                  " expected. Please change the shape of y to "
                  "(n_samples, ), for example using ravel().",
                  DataConversionWarning,
                  stacklevel=2,
              )
          return np.ravel(y)
  
      raise ValueError("bad input shape {0}".format(shape))
  
imports: import warnings
  import numbers
  import numpy
  import scipy.sparse
  from ..None import six
  from ...utils.exceptions import NotFittedError, NonBLASDotWarning, DataConversionWarning
label_desc: Use image node_id 12 for calling a global function with example usage: column_or_1d(y, warn) and returns: np, np