Left Square Bracket ([)

[ ...: Begin array

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Starts a high-rank array. Entries must be separated by , or . These must have the same shape. They become major cells of the result.

Must end with a corresponding ].

↗️
    ["abc", "def"]
┌─     
╵"abc  
  def" 
      ┘

    [4, 5]
Error: […]: Incompatible element shapes (encountered shapes ⟨4⟩ and ⟨5⟩)