input: Write a function to calculate the area of different shapes.
  assert calculate_area('rectangle', length=5, breadth=10) == 50
  assert calculate_area('square', side=4) == 16
  assert calculate_area('triangle', base=6, height=8) == 24
  assert calculate_area('circle', radius=3) == 28.26
output: def calculate_area(shape, **kwargs):
      if shape == 'rectangle':
          return kwargs['length'] * kwargs['breadth']
      elif shape == 'square':
          return kwargs['side'] ** 2
      elif shape == 'triangle':
          return 0.5 * kwargs['base'] * kwargs['height']
      elif shape == 'circle':
          return 3.14 * (kwargs['radius'] ** 2)