Modify -c command-line option to accept multiple inputs

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2020-05-08.19:08:57.598>
labels = ['interpreter-core', 'type-feature', '3.9']
title = 'Modify -c command-line option to accept multiple inputs'
updated_at = <Date 2020-05-23.16:30:57.898>
user = 'https://github.com/rhettinger'

bugs.python.org fields:

activity = <Date 2020-05-23.16:30:57.898>
actor = 'DahlitzFlorian'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Interpreter Core']
creation = <Date 2020-05-08.19:08:57.598>
creator = 'rhettinger'
dependencies = []
files = []
hgrepos = []
issue_num = 40568
keywords = []
message_count = 4.0
messages = ['368454', '368456', '368465', '369620']
nosy_count = 4.0
nosy_names = ['rhettinger', 'zach.ware', 'serhiy.storchaka', 'BTaskaya']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue40568'
versions = ['Python 3.9']