Wrapper for mash sketch.
    :param args: Files you want to sketch. Any number can be passed in, file patterns (i.e. *fasta) can be used.
    :param output_sketch: Output file for your sketch. Default sketch.msh.
    :param threads: Number of threads to run analysis on.
    :param kwargs: Other arguments, in parameter='argument' format. If parameter is just a switch, do parameter=''
    :param returncmd: If true, will return the command used to call mash as well as out and err.
    :return: stdout and stderr from mash sketch

def sketch(*args, output_sketch='sketch.msh', threads=1, returncmd=False, **kwargs):
    """
    Wrapper for mash sketch.
    :param args: Files you want to sketch. Any number can be passed in, file patterns (i.e. *fasta) can be used.
    :param output_sketch: Output file for your sketch. Default sketch.msh.
    :param threads: Number of threads to run analysis on.
    :param kwargs: Other arguments, in parameter='argument' format. If parameter is just a switch, do parameter=''
    :param returncmd: If true, will return the command used to call mash as well as out and err.
    :return: stdout and stderr from mash sketch
    """
    options = kwargs_to_string(kwargs)
    if len(args) == 0:
        raise ValueError('At least one file to sketch must be specified. You specified 0 files.')
    cmd = 'mash sketch '
    for arg in args:
        cmd += arg + ' '
    cmd += '-o {} -p {} {}'.format(output_sketch, str(threads), options)
    out, err = accessoryfunctions.run_subprocess(cmd)
    if returncmd:
        return out, err, cmd
    else:
        return out, err