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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def from_arrays(cls, **kwargs):
        '''Initialize a System from its constituent arrays. It is the
        fastest way to initialize a System, well suited for 
        reading one or more big System from data files.

        **Parameters**
        
        The following parameters are required:
        
        - type_array: An array of the types
        - maps: A dictionary that describes the relationships between 
                molecules in the system and atoms and bonds.
        
        **Example**
        
        This is how to initialize a System made of 3 water molecules::

                # Initialize the arrays that contain 9 atoms
                r_array = np.random.random((3, 9))
                type_array = ['O', 'H', 'H', 'O', 'H', 'H', 'O', 'H', 'H']
                
                # The maps tell us to which molecule each atom belongs to. In this 
                # example first 3 atoms belong to molecule 0, second 3 atoms
                # to molecule 1 and last 3 atoms to molecule 2.
                maps = {('atom', 'molecule') : [0, 0, 0, 1, 1, 1, 2, 2, 2]}
                System.from_arrays(r_array=r_array, 
                                   type_array=type_array,
                                   maps=maps)
                
                # You can also specify bonds, again with the its map that specifies
                # to to which molecule each bond belongs to.
                bonds = [[0, 1], [0, 2], [3, 4], [3, 5], [6, 7], [6, 8]]
                maps[('bond', 'molecule')] = [0, 0, 1, 1, 2, 2]
                System.from_arrays(r_array=r_array, 
                                   type_array=type_array,
                                   bonds=bonds,
                                   maps=maps)
                

        '''
        if 'mol_indices' in kwargs:
            raise DeprecationWarning('The mol_indices argument is deprecated, use maps instead. (See from_arrays docstring)')
        
        return super(System, cls).from_arrays(**kwargs)