def arraycopy(source, sourcepos, dest, destpos, numelem):
    """Python version of System.arraycopy() in Java.
    
    Parameters:
        source (list): source list to copy from.
        sourcepos (int): the position in source list to start copying.
        dest (list): destination list to copy to.
        destpos (int): the position in destination list to start copying.
        numelem (int): the data length to copy.
    """
    dest[destpos:destpos + numelem] = source[sourcepos:sourcepos + numelem]
