import re


def get_orbit_number(infile):
    """
    Look for an orbit number in the given filename.

    Parameters:
    ===========
    infile: str
        Input file.

    Returns:
    ========
    orbit: str
        Supposed orbit number
    """
    orbit = re.findall("[0-9]{6}", infile)[-1]  # Get orbit number
    return orbit