code: def vlcom3(a, v1, b, v2, c, v3):
      
      v1 = stypes.toDoubleVector(v1)
      v2 = stypes.toDoubleVector(v2)
      v3 = stypes.toDoubleVector(v3)
      sumv = stypes.emptyDoubleVector(3)
      a = ctypes.c_double(a)
      b = ctypes.c_double(b)
      c = ctypes.c_double(c)
      libspice.vlcom3_c(a, v1, b, v2, c, v3, sumv)
      return stypes.cVectorToPython(sumv)
docs: This subroutine computes the vector linear combination
      a*v1 + b*v2 + c*v3 of double precision, 3-dimensional vectors.
  
      http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/vlcom3_c.html
  
      :param a: Coefficient of v1 
      :type a: float
      :param v1: Vector in 3-space 
      :type v1: 3-Element Array of floats
      :param b: Coefficient of v2 
      :type b: float
      :param v2: Vector in 3-space 
      :type v2: 3-Element Array of floats
      :param c: Coefficient of v3 
      :type c: float
      :param v3: Vector in 3-space 
      :type v3: 3-Element Array of floats
      :return: Linear Vector Combination a*v1 + b*v2 + c*v3
      :rtype: 3-Element Array of floats