<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_rankings(self, limit=50, offset=0):
 """Get the overall ranking Args: limit (int):
 number of items to return (optional, defaults to 50) offset (int):
 number of items to skip (optional, defaults to 0) Returns: list of dicts: list of ranking items Each dict contains the following items: * id (`str`) * username (`str`) * nmrBurned (`decimal.Decimal`) * nmrPaid (`decimal.Decimal`) * nmrStaked (`decimal.Decimal`) * rep (`int`) * stakeCount (`int`) * usdEarned (`decimal.Decimal`) Example: [{'username': 'glasperlenspiel', 'usdEarned': Decimal('16347.12'), 'stakeCount': 41, 'rep': 14, 'nmrStaked': Decimal('250.000000000000000000'), 'nmrPaid': Decimal('16061.37'), 'nmrBurned': Decimal('295.400000000000000000'), 'id': 'bbee4f0e-f238-4d8a-8f1b-5eb384cdcbfc'}] """

        query = '''
            query($limit: Int!
                  $offset: Int!) {
              rankings(limit: $limit
                       offset: $offset) {
                username
                id
                nmrBurned
                nmrPaid
                nmrStaked
                rep
                stakeCount
                usdEarned
              }
            }
        '''
        arguments = {'limit': limit, 'offset': offset}
        data = self.raw_query(query, arguments)['data']['rankings']
        for item in data:
            for p in ["nmrBurned", "nmrPaid", "nmrStaked", "usdEarned"]:
                utils.replace(item, p, utils.parse_float_string)
        return data