Remove all contents in spellcheckable :chunks: from contents.

def _shadow_contents_from_chunks(contents, chunks, block_out_regexes=None):
    """Remove all contents in spellcheckable :chunks: from contents."""
    shadow_contents = [list(l) for l in contents]
    for chunk in chunks:
        char_offset = chunk.column
        line_offset = 0

        for index, line in enumerate(chunk.data):
            # Block out entire chunk range from shadow_contents
            for character_in_line in range(0, len(line)):
                shadow_line = chunk.line + line_offset
                shadow_char = char_offset + character_in_line
                shadow_contents[shadow_line][shadow_char] = 0

            # Also block out certain regexps from this chunk
            line = filter_nonspellcheckable_tokens(line,
                                                   block_out_regexes)
            chunk.data[index] = line

            line_offset += 1
            char_offset = 0

    return shadow_contents