'Convert the list of header lines into a dictionary'

def headers_to_dict(self, header_lines):

    headers = {}
    headers_list = [x for line in header_lines for x in line.split(':    ', 1)]
    headers_dict = dict(zip(headers_list[0::2], headers_list[1::2]))
    for header in headers_dict:
        headers[header.lower()] = headers_dict[header]
    return headers
