code: def test_gravity():
      N = ReferenceFrame("N")
      m, M, g = symbols("m M g")
      F1, F2 = dynamicsymbols("F1 F2")
      po = Point("po")
      pa = Particle("pa", po, m)
      A = ReferenceFrame("A")
      P = Point("P")
      I = outer(A.x, A.x)
      B = RigidBody("B", P, A, M, (I, P))
      forceList = [(po, F1), (P, F2)]
      forceList.extend(gravity(g * N.y, pa, B))
      l = [(po, F1), (P, F2), (po, g * m * N.y), (P, g * M * N.y)]
  
      for i in range(len(l)):
          for j in range(len(l[i])):
              assert forceList[i][j] == l[i][j]
  
file_path: sympy/sympy/physics/mechanics/tests/test_loads.py
imports: from pytest import raises
  from sympy import symbols
  from sympy.physics.mechanics import RigidBody, Particle, ReferenceFrame, Point, outer, dynamicsymbols, Force, Torque
  from sympy.physics.mechanics.loads import gravity, _parse_load
label_desc: Use image node_id 3 for calling a global function with example usage: test_gravity() without return types