new_contents: from feebb import *
  import matplotlib.pyplot as plt
  import itertools
  
  # Beam 1
  pre = Preprocessor()
  pre.load_json('ex_json/test2.json')
  elems = [Element(elem) for elem in pre.elements]
  print(pre.supports)
  beam = Beam(elems, pre.supports)
  post = Postprocessor(beam, 10)
  print(max(post.interp('moment')))
  print(min(post.interp('moment')))
  plt.plot(post.interp('moment'))
  plt.show()
  print(max(post.interp('shear')))
  print(min(post.interp('shear')))
  plt.plot(post.interp('shear'))
  plt.show()
  
  
  # Beam 1 submeshed
  pre = Preprocessor()
  pre.load_json('ex_json/test2.json')
  mesh = 100
  meshed = [Submesh(elem, mesh).submesh for elem in pre.elements]
  meshed_flat = list(itertools.chain.from_iterable(meshed))
  elems = [Element(elem) for elem in meshed_flat]
  meshed_supports = submesh_supports(pre.supports, mesh)
  beam = Beam(elems, meshed_supports)
  post = Postprocessor(beam, 2)
  print(max(post.interp('moment')))
  print(min(post.interp('moment')))
  plt.plot(post.interp('moment'))
  plt.show()
  print(max(post.interp('shear')))
  print(min(post.interp('shear')))
  plt.plot(post.interp('shear'))
  plt.show()
  
  # Beam 2 submeshed
  pre = Preprocessor()
  pre.load_json('ex_json/test.json')
  mesh = 100
  meshed = [Submesh(elem, mesh).submesh for elem in pre.elements]
  meshed_flat = list(itertools.chain.from_iterable(meshed))
  elems = [Element(elem) for elem in meshed_flat]
  meshed_supports = submesh_supports(pre.supports, mesh)
  beam = Beam(elems, meshed_supports)
  post = Postprocessor(beam, 2)
  print(max(post.interp('moment')))
  print(min(post.interp('moment')))
  plt.plot(post.interp('moment'))
  plt.show()
  print(max(post.interp('shear')))
  print(min(post.interp('shear')))
  plt.plot(post.interp('shear'))
  plt.show()
  
  # Beam 3 submeshed
  pre = Preprocessor()
  pre.load_json('ex_json/test3.json')
  mesh = 100
  meshed = [Submesh(elem, mesh).submesh for elem in pre.elements]
  meshed_flat = list(itertools.chain.from_iterable(meshed))
  elems = [Element(elem) for elem in meshed_flat]
  meshed_supports = submesh_supports(pre.supports, mesh)
  beam = Beam(elems, meshed_supports)
  post = Postprocessor(beam, 2)
  print(max(post.interp('moment')))
  print(min(post.interp('moment')))
  plt.plot(post.interp('moment'))
  plt.show()
  print(max(post.interp('shear')))
  print(min(post.interp('shear')))
  plt.plot(post.interp('shear'))
  plt.show()
  
subject: Change prelim tests