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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _cache_file(self, src_path):
 """ Load the data from `self._xml_roots` for `src_path`, if it hasn't been already. """

        # If we have not yet loaded this source file
        if src_path not in self._info_cache:
            # We only want to keep violations that show up in each xml source.
            # Thus, each time, we take the intersection.  However, to do this
            # we must treat the first time as a special case and just add all
            # the violations from the first xml report.
            violations = None

            # A line is measured if it is measured in any of the reports, so
            # we take set union each time and can just start with the empty set
            measured = set()

            # Loop through the files that contain the xml roots
            for xml_document in self._xml_roots:
                if xml_document.findall('.[@clover]'):
                    # see etc/schema/clover.xsd at  https://bitbucket.org/atlassian/clover/src
                    line_nodes = self._get_src_path_line_nodes_clover(xml_document, src_path)
                    _number = 'num'
                    _hits = 'count'
                elif xml_document.findall('.[@name]'):
                    # https://github.com/jacoco/jacoco/blob/master/org.jacoco.report/src/org/jacoco/report/xml/report.dtd
                    line_nodes = self._get_src_path_line_nodes_jacoco(xml_document, src_path)
                    _number = 'nr'
                    _hits = 'ci'
                else:
                    # https://github.com/cobertura/web/blob/master/htdocs/xml/coverage-04.dtd
                    line_nodes = self._get_src_path_line_nodes_cobertura(xml_document, src_path)
                    _number = 'number'
                    _hits = 'hits'
                if line_nodes is None:
                    continue

                # First case, need to define violations initially
                if violations is None:
                    violations = set(
                        Violation(int(line.get(_number)), None)
                        for line in line_nodes
                        if int(line.get(_hits, 0)) == 0)

                # If we already have a violations set,
                # take the intersection of the new
                # violations set and its old self
                else:
                    violations = violations & set(
                        Violation(int(line.get(_number)), None)
                        for line in line_nodes
                        if int(line.get(_hits, 0)) == 0
                    )

                # Measured is the union of itself and the new measured
                measured = measured | set(
                    int(line.get(_number)) for line in line_nodes
                )

            # If we don't have any information about the source file,
            # don't report any violations
            if violations is None:
                violations = set()

            self._info_cache[src_path] = (violations, measured)