'Determines whether the file is in lav format
LAV is an alignment format developed by Webb Miller\'s group. It is the primary output format for BLASTZ.
The first line of a .lav file begins with #:lav.
For complete details see http://www.bioperl.org/wiki/LAV_alignment_format
>>> from galaxy.datatypes.sniff import get_test_fname
>>> fname = get_test_fname( \'alignment.lav\' )
>>> Lav().sniff( fname )
True
>>> fname = get_test_fname( \'alignment.axt\' )
>>> Lav().sniff( fname )
False'

def sniff(self, filename):

    headers = get_headers(filename, None)
    try:
        if ((len(headers) > 1) and headers[0][0] and headers[0][0].startswith('#:lav')):
            return True
        else:
            return False
    except:
        return False
