"mark my word" meaning in English

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      "expansion": "mark my word",
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  "lang": "English",
  "lang_code": "en",
  "pos": "phrase",
  "senses": [
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      "alt_of": [
        {
          "word": "mark my words"
        }
      ],
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          "source": "w"
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      "examples": [
        {
          "ref": "2002, Beyblade, \"Day of the Dragoon\" (episode 2)",
          "text": "Tyson: Don't sweat it! Next time I meet up with that whoosh Kai, I'll show him who's king of the Blades! You mark my word, kid."
        }
      ],
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        "Alternative form of mark my words"
      ],
      "id": "en-mark_my_word-en-phrase-QbEAbHCN",
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        [
          "mark my words",
          "mark my words#English"
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        "(rare) Alternative form of mark my words"
      ],
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  "word": "mark my word"
}

{
  "head_templates": [
    {
      "args": {
        "1": "en",
        "2": "phrase"
      },
      "expansion": "mark my word",
      "name": "head"
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  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "phrase",
  "senses": [
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      "alt_of": [
        {
          "word": "mark my words"
        }
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        "English terms with rare senses"
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      "examples": [
        {
          "ref": "2002, Beyblade, \"Day of the Dragoon\" (episode 2)",
          "text": "Tyson: Don't sweat it! Next time I meet up with that whoosh Kai, I'll show him who's king of the Blades! You mark my word, kid."
        }
      ],
      "glosses": [
        "Alternative form of mark my words"
      ],
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          "mark my words",
          "mark my words#English"
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        "(rare) Alternative form of mark my words"
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  "word": "mark my word"
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