v2.0, 13. June 2021
1) add flags to racon:
   --no-trimming: turn off trimming
   --include-unpolished: if contig couldn't be polished output
   these flags are default.
2) change alignment format from paf to sam: get CIGAR string and base qualities in addition
3) add flag --debug: output all intermediary files
4) add flag --final: output all files from last round
5) if --debug and --final not set: final polished assembly and racon log file output

v2.1
1) add --trimming and --include_unpolished as command line options;
2) add memory usage function;
3) add output directory

v2.2
1) add --bam option

v2.3, 10. September 2021
1) add iterate_fasta function,
2) more type hinting,
3) check integer arguments are positive
4) cleanup while loop over polish rounds in polish function of raconrounds
5) add test data to directory test_data
6) add test script raconrounds.sh


TODO:
1) python binding for minimap2: https://github.com/lh3/minimap2/blob/master/python/mappy.pyx
2) python binding for racon: to be done
   https://pybind11.readthedocs.io/en/stable/index.html