code: def expand_dims(x, axis):
      """Expands dimensions of an input variable without copy.
  
      Args:
          x (:class:`~chainer.Variable` or :ref:`ndarray`): Input variable.
          axis (int):
              Position where new axis is to be inserted. The ``axis`` parameter
              is acceptable when :math:`-ndim - 1 \\leq axis \\leq ndim`.
              (``ndim`` is the dimension of input variables). When
              :math:`axis < 0`, the result is the same with
              :math:`ndim + 1 - |axis|`.
  
      Returns:
          ~chainer.Variable: Variable that holds an expanded input. The ``ndim``
          of output is one greater than that of ``x``.
  
      .. admonition:: Example
  
          >>> x = np.array([1, 2, 3])
          >>> x.shape
          (3,)
          >>> y = F.expand_dims(x, axis=0)
          >>> y.shape
          (1, 3)
          >>> y.array
          array([[1, 2, 3]])
          >>> y = F.expand_dims(x, axis=1)
          >>> y.shape
          (3, 1)
          >>> y.array
          array([[1],
                 [2],
                 [3]])
          >>> y = F.expand_dims(x, axis=-2)
          >>> y.shape
          (1, 3)
          >>> y.array
          array([[1, 2, 3]])
  
      """
      (y,) = ExpandDims(axis).apply((x,))
      return y
  
file_path: chainer/chainer/functions/array/expand_dims.py
imports: import chainer
  from chainer import backend
  from chainer import function_node
  from chainer.utils import type_check
label_desc: Use image node_id 1 for calling a global function with example usage: expand_dims(x, axis) and returns: y