@staticmethod
def __join_lines(line1, line2):
    """
        Method that joins two lines

        Parameters:
            line1 (numpy.array): 1D array.
            line2 (numpy.array): 1D array.

        Returns:
            numpy.array: line1 appended to the beginning of line2.
        """
    line2[0:0] = line1
    return line2
