def make_array(dims):
    """ Creates an array (dictionary with tuple coordinates as keys) of
    the given dimensions (the 3 dims together indicate how many values are
    to be inserted into outarr) initialized with None (value=None).
    For example, if dims given = (1 2 1),
    returned arr = {(0,0,0): None, (0,1,0): None}. If dims = (1,2,2), 4
    values are inserted. """
    arr = {}
    dim1, dim2, dim3 = dims
    for i in range(dim1):
        for j in range(dim2):
            for k in range(dim3):
                arr[i, j, k] = None
    return arr