def remove_separators(nhs_number):
    """Remove separators, if there are any, to go from e.g. 123-456-7890 to 1234567890."""
    if not nhs_number[3].isnumeric() and not nhs_number[7].isnumeric():
        return nhs_number[0:3] + nhs_number[4:7] + nhs_number[8:]
    else:
        return nhs_number