code: def sign(x, out=None, where=None, **kwargs):
      r"""
      Returns an element-wise indication of the sign of a number.
  
      The `sign` function returns ``-1 if x < 0, 0 if x==0, 1 if x > 0``.  nan
      is returned for nan inputs.
  
      For complex inputs, the `sign` function returns
      ``sign(x.real) + 0j if x.real != 0 else sign(x.imag) + 0j``.
  
      complex(nan, 0) is returned for complex nan inputs.
  
      Parameters
      ----------
      x : array_like
        Input values.
      out : Tensor, None, or tuple of Tensor and None, optional
          A location into which the result is stored. If provided, it must have
          a shape that the inputs broadcast to. If not provided or `None`,
          a freshly-allocated tensor is returned. A tuple (possible only as a
          keyword argument) must have length equal to the number of outputs.
      where : array_like, optional
          Values of True indicate to calculate the ufunc at that position, values
          of False indicate to leave the value in the output alone.
      **kwargs
  
      Returns
      -------
      y : Tensor
        The sign of `x`.
  
      Notes
      -----
      There is more than one definition of sign in common use for complex
      numbers.  The definition used here is equivalent to :math:`x/\sqrt{x*x}`
      which is different from a common alternative, :math:`x/|x|`.
  
      Examples
      --------
      >>> import mars.tensor as mt
  
      >>> mt.sign([-5., 4.5]).execute()
      array([-1.,  1.])
      >>> mt.sign(0).execute()
      0
      >>> mt.sign(5-2j).execute()
      (1+0j)
      """
      op = TensorSign(**kwargs)
      return op(x, out=out, where=where)
  
file_path: mars/mars/tensor/arithmetic/sign.py
imports: import numpy
  from ...None import opcodes
  from ..utils import infer_dtype
  from .core import TensorUnaryOp
  from .utils import arithmetic_operand
label_desc: Use image node_id 1 for calling a global function with example usage: sign(x, out, where) and returns: op