def set_fill_value(a, fill_value):
if isinstance(a, MaskedArray):<EOL><INDENT>a.set_fill_value(fill_value)<EOL><DEDENT>return<EOL>
Set the filling value of a, if a is a masked array.

This function changes the fill value of the masked array `a` in place.
If `a` is not a masked array, the function returns silently, without
doing anything.

Parameters
----------
a : array_like
    Input array.
fill_value : dtype
    Filling value. A consistency test is performed to make sure
    the value is compatible with the dtype of `a`.

Returns
-------
None
    Nothing returned by this function.

See Also
--------
maximum_fill_value : Return the default fill value for a dtype.
MaskedArray.fill_value : Return current fill value.
MaskedArray.set_fill_value : Equivalent method.

Examples
--------
>>> import numpy.ma as ma
>>> a = np.arange(5)
>>> a
array([0, 1, 2, 3, 4])
>>> a = ma.masked_where(a < 3, a)
>>> a
masked_array(data = [-- -- -- 3 4],
      mask = [ True  True  True False False],
      fill_value=999999)
>>> ma.set_fill_value(a, -999)
>>> a
masked_array(data = [-- -- -- 3 4],
      mask = [ True  True  True False False],
      fill_value=-999)

Nothing happens if `a` is not a masked array.

>>> a = range(5)
>>> a
[0, 1, 2, 3, 4]
>>> ma.set_fill_value(a, 100)
>>> a
[0, 1, 2, 3, 4]
>>> a = np.arange(5)
>>> a
array([0, 1, 2, 3, 4])
>>> ma.set_fill_value(a, 100)
>>> a
array([0, 1, 2, 3, 4])