code: def test_16857():
      if not jax:
          skip("JAX not installed")
  
      a_1 = MatrixSymbol("a_1", 10, 3)
      a_2 = MatrixSymbol("a_2", 10, 3)
      a_3 = MatrixSymbol("a_3", 10, 3)
      a_4 = MatrixSymbol("a_4", 10, 3)
      A = BlockMatrix([[a_1, a_2], [a_3, a_4]])
      assert A.shape == (20, 6)
  
      printer = JaxPrinter()
      assert (
          printer.doprint(A)
          == "jax.numpy.block([[a_1, a_2], [a_3, a_4]])"
      )
  
imports: from sympy.concrete.summations import Sum
  from sympy.core.mod import Mod
  from sympy.core.relational import Equality, Unequality
  from sympy.functions.elementary.miscellaneous import sqrt
  from sympy.functions.elementary.piecewise import Piecewise
  from sympy.matrices.expressions.blockmatrix import BlockMatrix
  from sympy.matrices.expressions.matexpr import MatrixSymbol
  from sympy.matrices.expressions.special import Identity
  from sympy.utilities.lambdify import lambdify
  from sympy.abc import x, i, j, a, b, c, d
  from sympy.core import Function, Pow, Symbol
  from sympy.codegen.matrix_nodes import MatrixSolve
  from sympy.codegen.numpy_nodes import logaddexp, logaddexp2
  from sympy.codegen.cfunctions import log1p, expm1, hypot, log10, exp2, log2, Sqrt
  from sympy.tensor.array import Array
  from sympy.tensor.array.expressions.array_expressions import ArrayTensorProduct, ArrayAdd, PermuteDims, ArrayDiagonal
  from sympy.printing.numpy import JaxPrinter, _jax_known_constants, _jax_known_functions
  from sympy.tensor.array.expressions.from_matrix_to_array import convert_matrix_to_array
  from sympy.testing.pytest import skip, raises
  from sympy.external import import_module
label_desc: Use image node_id 19 for calling a global function with example usage: test_16857() without return types