title: python XML parse error: 'ParseError: unbound prefix:' (Can't find any issue with xml file)
body: <p>Hi I am getting following error when I parse the following xml file, (Can't find any issue with xml file). I want this xml to pass parsing with out fail.
  I am using xml.etree for parsing and I am using formstring method in etree.
  i am using :</p>
  
  <pre><code>import xml.etree.ElementTree as ET
  root_payload = ET.fromstring(xml_file)
  </code></pre>
  
  <p>PLEASE HELP.</p>
  
  <pre><code>&lt;!--
  TRACE CONFIGS EXAMPLE OF TURN ON DEBUG TRACING LEVELS
  
  Global Variables to be replaced in this document:
  $pmaa_ip_addr$ - Controlling PMAA IP Address
  $auth$ - Authorization key for the PMAA interface
  $dpu_ident$ - DPU unique identifier
  
  Command: https://$pmaa_ip_addr$:8443/dpudatastore/id=PMA-$dpu_ident$/restconf/data/adtran-subsystem-traces:traces
  Request: PUT
  Authorization: Basic $auth$
  Accept: application/xrd+xml
  Content-Type: application/xrd+xml--&gt;
  &lt;adtn-subs-trace:traces xmlms:adtn-subs-trace="http://www.adtran.com/ns/yang/adtran-subsystem-traces"&gt;
  &lt;adtn-subs-trace:trace&gt;
      &lt;!-- 
      subsystem - Identifies Adtran subsystem to be traced. See Adtran for list of valid subsystems
      scope - Possible values (msg, event, protocol, data, stats,  misc, debug, startup)
      level - Possible values (none, normal, detailed, extensive)
      --&gt;
      &lt;adtn-subs-trace:subsystem&gt;configuration&lt;/adtn-subs-trace:subsystem&gt;
      &lt;adtn-subs-trace:subsystem-trace&gt;
          &lt;adtn-subs-trace:scope&gt;msg&lt;/adtn-subs-trace:scope&gt;
          &lt;adtn-subs-trace:level&gt;none&lt;/adtn-subs-trace:level&gt;
      &lt;/adtn-subs-trace:subsystem-trace&gt;
      &lt;adtn-subs-trace:subsystem-trace&gt;
          &lt;adtn-subs-trace:scope&gt;event&lt;/adtn-subs-trace:scope&gt;
          &lt;adtn-subs-trace:level&gt;none&lt;/adtn-subs-trace:level&gt;
      &lt;/adtn-subs-trace:subsystem-trace&gt;
      &lt;adtn-subs-trace:subsystem-trace&gt;
          &lt;adtn-subs-trace:scope&gt;protocol&lt;/adtn-subs-trace:scope&gt;
          &lt;adtn-subs-trace:level&gt;none&lt;/adtn-subs-trace:level&gt;
      &lt;/adtn-subs-trace:subsystem-trace&gt;
      &lt;adtn-subs-trace:subsystem-trace&gt;
          &lt;adtn-subs-trace:scope&gt;data&lt;/adtn-subs-trace:scope&gt;
          &lt;adtn-subs-trace:level&gt;none&lt;/adtn-subs-trace:level&gt;
      &lt;/adtn-subs-trace:subsystem-trace&gt;
      &lt;adtn-subs-trace:subsystem-trace&gt;
          &lt;adtn-subs-trace:scope&gt;stats&lt;/adtn-subs-trace:scope&gt;
          &lt;adtn-subs-trace:level&gt;none&lt;/adtn-subs-trace:level&gt;
      &lt;/adtn-subs-trace:subsystem-trace&gt;
      &lt;adtn-subs-trace:subsystem-trace&gt;
          &lt;adtn-subs-trace:scope&gt;misc&lt;/adtn-subs-trace:scope&gt;
          &lt;adtn-subs-trace:level&gt;none&lt;/adtn-subs-trace:level&gt;
      &lt;/adtn-subs-trace:subsystem-trace&gt;
      &lt;adtn-subs-trace:subsystem-trace&gt;
          &lt;adtn-subs-trace:scope&gt;debug&lt;/adtn-subs-trace:scope&gt;
          &lt;adtn-subs-trace:level&gt;none&lt;/adtn-subs-trace:level&gt;
      &lt;/adtn-subs-trace:subsystem-trace&gt;
      &lt;adtn-subs-trace:subsystem-trace&gt;
          &lt;adtn-subs-trace:scope&gt;startup&lt;/adtn-subs-trace:scope&gt;
          &lt;adtn-subs-trace:level&gt;none&lt;/adtn-subs-trace:level&gt;
      &lt;/adtn-subs-trace:subsystem-trace&gt;
  &lt;/adtn-subs-trace:trace&gt;
  &lt;/adtn-subs-trace:traces&gt;
  </code></pre>
  
  <p>Error is as follows..</p>
  
  <pre><code>Traceback (most recent call last):
  File "C:/Users/uvijayac/Desktop/REST/r3.py", line 149, in &lt;module&gt;
  x.main(param_dict)
  File "C:/Users/uvijayac/Desktop/REST/r3.py", line 114, in main
  root_payload = ET.fromstring(request_dict[file_name]['payload'])
  File "C:\Python27\lib\xml\etree\ElementTree.py", line 1300, in XML
  parser.feed(text)
  File "C:\Python27\lib\xml\etree\ElementTree.py", line 1642, in feed
  self._raiseerror(v)
  File "C:\Python27\lib\xml\etree\ElementTree.py", line 1506, in _raiseerror
  raise err
  xml.etree.ElementTree.ParseError: unbound prefix: line 15, column 0
  </code></pre>