def _handle_continuation(line, col, form):
    """Modify column and format string to account for a continuation block.

    The PDB format specifies, that `Continuation` fields are intended by
    one char, which (in `.PDBRecordLibrary`) is marked by a trailing `c` in the
    format string. Example: ``<{10}s`` <--> ``<{10}sc``.  If the `c` is present
    and if there is a continuation number in the preceeding column, the data
    field is moved by one char to the right.  In any case, the trailing `c` is
    removed from the format string.

    """
    out_col = list(col)
    if form.endswith('c'):
        out_form = form[:-1]
        if line[col[0] - 1].strip():
            out_col[0] += 1
            out_col[1] += 1
    else:
        out_form = form
    return out_col, out_form
