def _define_range(self, sequences):
sequence_count = <NUM_LIT:0><EOL>total_sequence = <NUM_LIT:0><EOL>for record in SeqIO.parse(open(sequences), '<STR_LIT>'): <EOL><INDENT>total_sequence+=<NUM_LIT:1> <EOL>sequence_count+=len(record.seq) <EOL><DEDENT>max_range = (sequence_count/total_sequence)*<NUM_LIT><EOL>return max_range<EOL>
define_range - define the maximum range within which two hits in a db
search can be linked. This is defined as 1.5X the average length of all
reads in the database.

Parameters
----------
sequences : str
    A path to the sequences in FASTA format. This fasta file is assumed
    to be in the correct format. i.e. headers start with '>'

Returns
-------
max_range : int
    As described above, 1.5X the size of the average length of genes
    within the database