R/file_contains_dna.R
    file_contains_dna.RdCheck whether input file contains dna as required.
file_contains_dna(file, input_type)file path to fasta file.
a character string specifying whether input file a "query" or "subject" file.
When a file contains the correct sequence type then this function will only execute without any output. In case a file does not contains the correct sequence type then an error is thrown.
# test an dna file
file_contains_dna(file = system.file('seqs/qry_nn.fa', package = 'metablastr'),
                  input_type = "query")