code: def _as2d(ar):
      """
      If the input array is 2D return it, if it is 1D, append a dimension,
      making it a column vector.
      """
      if ar.ndim == 2:
          return ar
      else:  # Assume 1!
          aux = cupy.array(ar, copy=False)
          aux.shape = (ar.shape[0], 1)
          return aux
  
file_path: cupy/cupyx/scipy/sparse/linalg/_lobpcg.py
imports: import warnings
  import numpy
  import cupy
  import cupy.linalg
  from cupyx.scipy.sparse import linalg
label_desc: Use image node_id 4 for calling a global function with example usage: _as2d(ar) and returns: ar, aux