In this program, you should be able to open any FASTA file by inputting the command fasta and the file name (so the command line is "fasta filename") and

1) verify that the user entered a filename and that the file can be opened. If not, print informative error messages and exit.

2) Read the contents of the file, print the name, standard sequence, reverse sequence and complement sequence.

3) limit the length of each line of sequence to 80 characters. The label line (line beginning with a ">") can be longer.

4) add the sequence length L in basepairs to the end of the sequence label line (line beginning with a ">") using a format of ">DNA name, length(#) bp"