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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 find_assign(data, varname):
 """Finds a substring that looks like an assignment. :param data: Source to search in. :param varname: Name of the variable for which an assignment should be found. """

    ASSIGN_RE = re.compile(BASE_ASSIGN_PATTERN.format(varname))

    if len(ASSIGN_RE.findall(data)) > 1:
        raise PluginError('Found multiple {}-strings.'.format(varname))

    if len(ASSIGN_RE.findall(data)) < 1:
        raise PluginError('No version assignment ("{}") found.'
                          .format(varname))

    return ASSIGN_RE.search(data).group(2)