def load(self, filename, create_if_missing=True):
        filename = Path(filename)
        if not filename.exists() and create_if_missing:
            self.load_pip_requirements()
            with filename.open("w") as f:
                f.write(yaml.dump(self.serialized, default_flow_style=False,
                                  encoding=None))
            self.filename = filename
            return self.save(filename)
        with filename.open() as f:
            for group, requirements in yaml.load(f.read()).items():
                for requirement in requirements:
                    self[group].add(Requirement.coerce(requirement))
        self.filename = filename
def render(self, context):
        try:
            if self.params:
                params = template.Variable(self.params).resolve(context)
            else:
                params = {}

            # try matching an address string literal
            email_literal = self.email.strip().lower()
            if EMAIL_RE.match(email_literal):
                email = email_literal
            # treat as a variable
            else:
                email = template.Variable(self.email).resolve(context)
        except template.VariableDoesNotExist:
            return ''

        # now, we generate the gravatar url
        return _build_gravatar_url(email, params)