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##### SUMMARY
<!--- Explain the problem briefly below -->
Fix iosxr interfaces zuul failure, which is failing coz of lowercase `loopback` instead of `Loopback` in iosxr. (ref: https://logs.zuul.ansible.com/03/61303/28b181fe1fcb3831516b336923ce39e29942ee50/third-party-check/ansible-test-network-integration-iosxr-python27/80fc31b/controller/ara-report/reports/01641385-035c-4e22-a0bd-fdfbf67a8cb9.html)
##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
<!--- Write the short name of the module, plugin, task or feature below, use your best guess if unsure -->
iosxr_interfaces
##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
devel
```

##### CONFIGURATION
<!--- Paste verbatim output from "ansible-config dump --only-changed" between quotes -->
```paste below

```

##### OS / ENVIRONMENT
<!--- Provide all relevant information below, e.g. target OS versions, network device firmware, etc. -->
zuul

##### STEPS TO REPRODUCE
<!--- Describe exactly how to reproduce the problem, using a minimal test-case -->

<!--- Paste example playbooks or commands between quotes below -->
```yaml

```

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##### EXPECTED RESULTS
<!--- Describe what you expected to happen when running the steps above -->
iosxr_interfaces should pass as expected

##### ACTUAL RESULTS
<!--- Describe what actually happened. If possible run with extra verbosity (-vvvv) -->
iosxr_interfaces fails
<!--- Paste verbatim command output between quotes -->
```paste below

```

#
"""
The iosxr interfaces fact class
It is in this file the configuration is collected from the device
for a given resource, parsed, and the facts tree is populated
based on the configuration.
"""
from __future__ import absolute_import, division, print_function
__metaclass__ = type
from copy import deepcopy
import re
from ansible.module_utils.network.common import utils
from ansible.module_utils.network.iosxr.utils.utils import get_interface_type, normalize_interface
from ansible.module_utils.network.iosxr.argspec.interfaces.interfaces import InterfacesArgs
class InterfacesFacts(object):
    """ The iosxr interfaces fact class
    """
    def __init__(self, module, subspec='config', options='options'):
        self._module = module
        self.argument_spec = InterfacesArgs.argument_spec
        spec = deepcopy(self.argument_spec)
        if subspec:
            if options:
                facts_argument_spec = spec[subspec][options]
            else:
                facts_argument_spec = spec[subspec]
        else:
            facts_argument_spec = spec
        self.generated_spec = utils.generate_dict(facts_argument_spec)
    def populate_facts(self, connection, ansible_facts, data=None):