input: Write a python function to simulate a three-body system with gravitational interactions and return the trajectory of the first body. 
  assert simulateSystem([0, 0], [0, 0], [1, 0], [0, 1], [0, 1], [-1, 0], 100) is not None
  assert isinstance(simulateSystem([0, 0], [0, 0], [1, 0], [0, 1], [0, 1], [-1, 0], 100), tuple)
  assert len(simulateSystem([0, 0], [0, 0], [1, 0], [0, 1], [0, 1], [-1, 0], 100)[0]) == 100
output: def simulateSystem(p1, v1, p2, v2, p3, v3, steps):
      import numpy as np
  
      G = 1.0  # Gravitational constant
  
      def gravitational_acceleration(p1, p2):
          """Compute the gravitational acceleration on p1 due to the mass at p2."""
          r = np.array(p2) - np.array(p1)
          dist = np.linalg.norm(r)
          if dist == 0:
              return np.array([0.0, 0.0])
          return G * r / dist**3
  
      positions1 = []
  
      p1, p2, p3 = np.array(p1, dtype=float), np.array(p2, dtype=float), np.array(p3, dtype=float)
      v1, v2, v3 = np.array(v1, dtype=float), np.array(v2, dtype=float), np.array(v3, dtype=float)
  
      for _ in range(steps):
          # Store the current position of the first body
          positions1.append(p1.copy())
  
          # Compute accelerations
          a1 = gravitational_acceleration(p1, p2) + gravitational_acceleration(p1, p3)
          a2 = gravitational_acceleration(p2, p1) + gravitational_acceleration(p2, p3)
          a3 = gravitational_acceleration(p3, p1) + gravitational_acceleration(p3, p2)
  
          # Update velocities
          v1 += a1
          v2 += a2
          v3 += a3
  
          # Update positions
          p1 += v1
          p2 += v2
          p3 += v3
  
      return (positions1,)