<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def open(pattern, read_only=False):
 """ Return a root descriptor to work with one or multiple NetCDF files. Keyword arguments: pattern -- a list of filenames or a string pattern. """

    root = NCObject.open(pattern, read_only=read_only)
    return root, root.is_new