parameters: (arr, pad_amt, val, axis=-1)
return_statement: return _do_prepend(arr, np.full(padshape, val, dtype=arr.dtype), axis)
docstring: Prepend constant `val` along `axis` of `arr`.
  
      Parameters
      ----------
      arr : ndarray
          Input array of arbitrary shape.
      pad_amt : int
          Amount of padding to prepend.
      val : scalar
          Constant value to use. For best results should be of type `arr.dtype`;
          if not `arr.dtype` will be cast to `arr.dtype`.
      axis : int
          Axis along which to pad `arr`.
  
      Returns
      -------
      padarr : ndarray
          Output array, with `pad_amt` constant `val` prepended along `axis`.
docstring_summary: Prepend constant `val` along `axis` of `arr`.
docstring_tokens: Prepend constant val along axis of arr .
function: def _prepend_const(arr, pad_amt, val, axis=-1):
      """
      Prepend constant `val` along `axis` of `arr`.
  
      Parameters
      ----------
      arr : ndarray
          Input array of arbitrary shape.
      pad_amt : int
          Amount of padding to prepend.
      val : scalar
          Constant value to use. For best results should be of type `arr.dtype`;
          if not `arr.dtype` will be cast to `arr.dtype`.
      axis : int
          Axis along which to pad `arr`.
  
      Returns
      -------
      padarr : ndarray
          Output array, with `pad_amt` constant `val` prepended along `axis`.
  
      """
      if pad_amt == 0:
          return arr
      padshape = tuple(x if i != axis else pad_amt
                       for (i, x) in enumerate(arr.shape))
      return _do_prepend(arr, np.full(padshape, val, dtype=arr.dtype), axis)
function_tokens: def _prepend_const ( arr , pad_amt , val , axis = - 1 ) : if pad_amt == 0 : return arr padshape = tuple ( x if i != axis else pad_amt for ( i , x ) in enumerate ( arr . shape ) ) return _do_prepend ( arr , np . full ( padshape , val , dtype = arr . dtype ) , axis )