# one backreference to group 1 (that's two 2\ ).
new_header = re.sub("@code\{\\\\([a-zA-Z])", "@code{\\\\\\\\\\1", header)
escaped_snippet = (snippet[:header_char_number_start] +
# one backreference to group 1 (that's two 2\ ).
new_header = re.sub("@code\{\\\\([a-zA-Z])", "@code{\\\\\\\\\\1", header)
escaped_snippet = (snippet[:header_char_number_start] +