<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def substitute_params(self, substitutions):
 """Substitute param values in our param_dict from params Args: substitutions (Map or dict):
 Values to substitute. E.g. Map of {"name": "me"} E.g. if self.param_dict is: {"name": "$(name):
pos", "exposure": 1.0} And substitutions is: {"name": "me"} After the call self.param_dict will be: {"name": "me:pos", "exposure": 1.0} """

        param_dict = {}
        # TODO: this should be yaml.add_implicit_resolver()
        for k, v in self.param_dict.items():
            param_dict[k] = replace_substitutions(v, substitutions)
        return param_dict