"""Groups lines of an SDP (Session Description Protocol) string into session and media sections.

This function processes an SDP string by splitting it into lines and categorizing each line into either the session section or one of the media sections. Lines starting with "m=" are considered media lines, and all subsequent lines until the next "m=" line are grouped under that media section. Lines before the first "m=" line are considered part of the session section.

Args:
    sdp (str): The SDP string to be processed.

Returns:
    tuple[list[str], list[list[str]]]: A tuple containing two elements:
        - The first element is a list of strings representing the session section.
        - The second element is a list of lists of strings, where each inner list represents a media section.

Example:
    >>> grouplines('m=audio 49170 RTP/AVP 0')
    ([], [['m=audio 49170 RTP/AVP 0']])
    >>> grouplines('m=video 51372 RTP/AVP 99\\na=rtpmap:99 h263-1998/90000')
    ([], [['m=video 51372 RTP/AVP 99', 'a=rtpmap:99 h263-1998/90000']])
    >>> grouplines('c=IN IP4 192.0.2.3\\nm=audio 49170 RTP/AVP 0')
    (['c=IN IP4 192.0.2.3'], [['m=audio 49170 RTP/AVP 0']])
    >>> grouplines('s=Session SDP\\nt=0 0\\nm=audio 49170 RTP/AVP 0')
    (['s=Session SDP', 't=0 0'], [['m=audio 49170 RTP/AVP 0']])
"""
You should write code starting with:
from typing import List, Tuple

def grouplines(sdp: str) -> Tuple[List[str], List[List[str]]]:
    pass

