Check if coo is (M, 3) ndarray

def load_matrix_sparse(filename):
    coo = np.load(filename)

    """Check if coo is (M, 3) ndarray"""
    if len(coo.shape) == 2 and coo.shape[1] == 3:
        row = coo[:, 0]
        col = coo[:, 1]
        values = coo[:, 2]

        """Check if imaginary part of row and col is zero"""
        if np.all(np.isreal(row)) and np.all(np.isreal(col)):
            row = row.real
            col = col.real

            """Check if first and second column contain only integer entries"""
            if np.all(is_integer(row)) and np.all(is_integer(col)):

                """Convert row and col to int"""
                row = row.astype(int)
                col = col.astype(int)

                """Create coo-matrix"""
                A = scipy.sparse.coo_matrix((values, (row, col)))
                return A
            else:
                raise ValueError('File contains non-integer entries for row and col.')
        else:
            raise ValueError('File contains complex entries for row and col.')
    else:
        raise ValueError('Given file is not a sparse matrix in coo-format.')