def pseudo_gem(start_loc, frag_lengths, f2f_dist):
    """
    Create a pseudo-GEM on a random start location.
    Args:
       start_loc (int): random start location on the genome (ex: 390)
       frag_lengths (list): lengths of each fragments (ex: [100, 200, 150])
       f2f_dist (list): fragment to fragment distances (ex: [1000, 4000])
    Returns:
       pseudo_gem (list): start and end of fragments in a list
                     (ex: [390,490,1490,1690,5690,5840])
    """
    f2f_dist.append(0)
    pseudo_gem = []
    left_coord = start_loc
    for i in range(len(frag_lengths)):
        right_coord = left_coord + frag_lengths[i]
        pseudo_gem.extend([left_coord, right_coord])
        left_coord = right_coord + f2f_dist[i]
    return(pseudo_gem)