\1 in key_value used in group name path_string

[myxx921]

hi, if key_value contains \1, \2 , \3 , etc.
and this key_value is used to compose get error

from ttp import ttp
from pprint import pprint

data = r"""
routing-instances {
    "some_routing_instance_70\1" {
        instance-type vrf;
    }
}
"""

template = """
<group name="interfaces.{{ ri }}**">
routing-instances {{ ignore }} 
    {{ ri | _start_ }} { 
    } {{ _end_ }}
</group>
"""

parser = ttp(data, template)
parser.parse()
output = parser.result()
pprint(output)

---------------------------------error-------------------------------------------------------

I changed the output to see what we got as input

raise s.error(f"{source} {state} {type(state)} invalid group reference %d" % index, pos)
re.error: "some_routing_instance_70\1" re.compile('{{\sri\s}}') <class 're.Pattern'> invalid group reference 1 at position 26