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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 parse(self, requires_cfg=True):
 """Parse the configuration sources into `Bison`. Args: requires_cfg (bool):
 Specify whether or not parsing should fail if a config file is not found. (default: True) """

        self._parse_default()
        self._parse_config(requires_cfg)
        self._parse_env()