Lists BioMart datasets.

    :param host: address of the host server, default='http://www.ensembl.org/biomart'

    :returns: nothing

def datasetsBM(host=biomart_host):
    """
    Lists BioMart datasets.

    :param host: address of the host server, default='http://www.ensembl.org/biomart'

    :returns: nothing

    """
    stdout_ = sys.stdout #Keep track of the previous value.
    stream = StringIO()
    sys.stdout = stream   
    server = BiomartServer(biomart_host)
    server.show_datasets()
    sys.stdout = stdout_ # restore the previous stdout.
    variable = stream.getvalue() 
    v=variable.replace("{"," ") 
    v=v.replace("}"," ") 
    v=v.replace(": ","\t")
    print(v)