Content-Type: multipart/mixed; boundary="1"
MIME-Version: 1.0

--1
Content-Type: text/plain

hello, world
--1
Content-Type: multipart/mixed; boundary="1"
MIME-Version: 2.0

--1
Content-Type: text/plain

hello, world
--1
Content-Type: multipart/mixed; boundary="1"
MIME-Version: abc

--1
Content-Type: text/plain

hello, world
--1
Content-Type: multipart/mixed; boundary="1"
MIME-Version:

--1
Content-Type: text/plain

hello, world
--1

---- EXPECTED STRUCTURE ----
{
  "headers_rfc": {
    "content_type": {
      "ContentType": {
        "c_type": "multipart",
        "c_subtype": "mixed",
        "attributes": {
          "boundary": "1"
        }
      }
    },
    "mime_version": {
      "Text": "1.0"
    }
  },
  "headers_offsets": [
    {
      "name": {
        "Rfc": "content_type"
      },
      "start": 13,
      "end": 44
    },
    {
      "name": {
        "Rfc": "mime_version"
      },
      "start": 57,
      "end": 62
    }
  ],
  "html_body": [
    0,
    2,
    4,
    6
  ],
  "text_body": [
    0,
    2,
    4,
    6
  ],
  "parts": [
    {
      "Text": {
        "headers": {
          "content_type": {
            "ContentType": {
              "c_type": "text",
              "c_subtype": "plain"
            }
          }
        },
        "body": "hello, world"
      }
    },
    {
      "Multipart": {
        "mime_version": {
          "Text": "2.0"
        },
        "content_type": {
          "ContentType": {
            "c_type": "multipart",
            "c_subtype": "mixed",
            "attributes": {
              "boundary": "1"
            }
          }
        }
      }
    },
    {
      "Text": {
        "headers": {
          "content_type": {
            "ContentType": {
              "c_type": "text",
              "c_subtype": "plain"
            }
          }
        },
        "body": "hello, world"
      }
    },
    {
      "Multipart": {
        "content_type": {
          "ContentType": {
            "c_type": "multipart",
            "c_subtype": "mixed",
            "attributes": {
              "boundary": "1"
            }
          }
        },
        "mime_version": {
          "Text": "abc"
        }
      }
    },
    {
      "Text": {
        "headers": {
          "content_type": {
            "ContentType": {
              "c_type": "text",
              "c_subtype": "plain"
            }
          }
        },
        "body": "hello, world"
      }
    },
    {
      "Multipart": {
        "content_type": {
          "ContentType": {
            "c_type": "multipart",
            "c_subtype": "mixed",
            "attributes": {
              "boundary": "1"
            }
          }
        }
      }
    },
    {
      "Text": {
        "headers": {
          "content_type": {
            "ContentType": {
              "c_type": "text",
              "c_subtype": "plain"
            }
          }
        },
        "body": "hello, world"
      }
    }
  ],
  "structure": {
    "MultiPart": [
      5,
      [
        {
          "Part": 6
        }
      ]
    ]
  },
  "offset_header": 0,
  "offset_body": 63,
  "offset_end": 436
}