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  GBMatrix{T, F} <: AbstractSparseArray{T, UInt64, 2}

  Two-dimensional GraphBLAS array with elements of type T. F is the type of the fill-value, which is typically Nothing or T. Internal
  representation is specified as opaque, but in this implementation is stored as one of the following in either row or column orientation:

  1. Dense
  2. Bitmap
  3. Sparse Compressed
  4. Hypersparse

  The storage type is automatically determined by the library.