def _get_BD_range(x):
    """Getting the BD range from a fraction ID 
    (eg., "1.710-1.716").

    Parameters
    ----------
    x : str
        fraction ID

    Returns
    -------
    tuple -- BD start, middle end
    """
    if x.startswith('-'):
        [start,_,end] = x.rpartition('-')
    else:
        [start,_,end] = x.partition('-')            
        
    if start.startswith('-inf'):
        end = round(float(end),3) - 0.001
        end = round(end,3)
        mid = end
    elif end.endswith('inf'):
        start = round(float(start),3) + 0.001
        start = round(start, 3)
        mid = start
    else:
        start = round(float(start),3)
        end = round(float(end),3)
        mid = round((end - start)/2 + start,3)
        
    return start, mid, end