Parse the provided files for the corresponding strings.

def parse_single(self, errmsg):
        """
        Parse the provided files for the corresponding strings.
        """
        found = False
        message = None
        metadata = None
        for k in errmsg.keys():
            if self.files[k] is not None:
                #print('parsing ', self.files[k], ' for ', errmsg[k]['string'])
                try:
                    with open(self.files[k], mode='r') as f:
                        lines = f.read().split('\n')
                    for line in lines:
                        if errmsg[k]['string'] in line:
                            message = line
                            found = True
                    if found:
                        metadata = self.extract_metadata(lines, errmsg[k]['meta_filter'])
                except (IOError, OSError):
                    print(self.files[k], 'not found')
                    pass
                except TypeError:
                    print('type error', self.files[k], ' has type ', self.files[k].cls(), ' should be string.')
                    pass

        return found, message, metadata