def calculate_windows(self, **kwargs):
windows = find_windows(self.elements, self.coordinates, **kwargs)<EOL>if windows:<EOL><INDENT>self.properties.update(<EOL>{<EOL>'<STR_LIT>': {<EOL>'<STR_LIT>': windows[<NUM_LIT:0>], '<STR_LIT>': windows[<NUM_LIT:1>],<EOL>}<EOL>}<EOL>)<EOL>return windows[<NUM_LIT:0>]<EOL><DEDENT>else:<EOL><INDENT>self.properties.update(<EOL>{'<STR_LIT>': {'<STR_LIT>': None,  '<STR_LIT>': None, }}<EOL>)<EOL><DEDENT>return None<EOL>
Return the diameters of all windows in a molecule.

This function first finds and then measures the diameters of all the
window in the molecule.

Returns
-------
:class:`numpy.array`
    An array of windows' diameters.

:class:`NoneType`
    If no windows were found.