Sample Input::

            TimeoutStartUSec=1min 30s
            LimitNOFILE=65536
            LimitMEMLOCK=
            LimitLOCKS=18446744073709551615

        Sample Output::

            {"LimitNOFILE"     : "65536",
            "TimeoutStartUSec" : "1min 30s",
            "LimitLOCKS"       : "18446744073709551615"}

        In CMD's output, empty properties are suppressed by default.
        We will also suppressed empty properties in return data.

def parse_content(self, content):
        """
        Sample Input::

            TimeoutStartUSec=1min 30s
            LimitNOFILE=65536
            LimitMEMLOCK=
            LimitLOCKS=18446744073709551615

        Sample Output::

            {"LimitNOFILE"     : "65536",
            "TimeoutStartUSec" : "1min 30s",
            "LimitLOCKS"       : "18446744073709551615"}

        In CMD's output, empty properties are suppressed by default.
        We will also suppressed empty properties in return data.
        """
        data = {}
        data = split_kv_pairs(content, use_partition=False)

        """Remove empty key"""
        self.data = dict((k, v) for k, v in data.items() if not v == '')