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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 core(self, key, value):
 """Populate the ``core`` key. Also populates the ``deleted`` and ``project_type`` keys through side effects. """

    core = self.get('core')
    deleted = self.get('deleted')
    project_type = self.get('project_type', [])

    if not core:
        normalized_a_values = [el.upper() for el in force_list(value.get('a'))]
        if 'CORE' in normalized_a_values:
            core = True

    if not deleted:
        normalized_c_values = [el.upper() for el in force_list(value.get('c'))]
        if 'DELETED' in normalized_c_values:
            deleted = True

    if not project_type:
        normalized_a_values = [el.upper() for el in force_list(value.get('a'))]
        if 'ACCELERATOR' in normalized_a_values:
            project_type.append('accelerator')

    self['project_type'] = project_type
    self['deleted'] = deleted
    return core