build_graph             Make a graph which refers relationship of
                        sentences. Vertex refers one sentence, and edge
                        refers co-occurence between two sentences.
                        Example will be shown in github.
co_occurence            Calculate a Jaccard Index between two
                        sentences. Example will be shown in github.
get_sentences           Make character string list which ends with a
                        period, from the whole text. Example will be
                        shown in github.
sentence2table          Convert sentence to noun word table except
                        stopword. Example will be shown in github.
summarize               Return list of character string of the most
                        important sentences by Textrank algorithm.
                        Example will be shown in github.
table2gset              Convert sentence to word table except stopword.
                        Example will be shown in github.
xplit                   Separate text into sentence list by delimiter.
                        Example will be shown in github.
