class_docstr: Represents integral of a scalar or vector field
  over a Parametric Region
  
  Examples
  ========
  
  >>> from sympy import cos, sin, pi
  >>> from sympy.vector import CoordSys3D, ParametricRegion, ParametricIntegral
  >>> from sympy.abc import r, t, theta, phi
  
  >>> C = CoordSys3D('C')
  >>> curve = ParametricRegion((3*t - 2, t + 1), (t, 1, 2))
  >>> ParametricIntegral(C.x, curve)
  5*sqrt(10)/2
  >>> length = ParametricIntegral(1, curve)
  >>> length
  sqrt(10)
  >>> semisphere = ParametricRegion((2*sin(phi)*cos(theta), 2*sin(phi)*sin(theta), 2*cos(phi)),                            (theta, 0, 2*pi), (phi, 0, pi/2))
  >>> ParametricIntegral(C.z, semisphere)
  8*pi
  
  >>> ParametricIntegral(C.j + C.k, ParametricRegion((r*cos(theta), r*sin(theta)), r, theta))
  0
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code: def field(self):
      return self.args[0]
  
file_path: sympy/sympy/vector/integrals.py
imports: from sympy.core import Basic, diff
  from sympy.core.singleton import S
  from sympy.core.sorting import default_sort_key
  from sympy.matrices import Matrix
  from sympy.integrals import Integral, integrate
  from sympy.geometry.entity import GeometryEntity
  from sympy.simplify.simplify import simplify
  from sympy.utilities.iterables import topological_sort
  from sympy.vector import CoordSys3D, Vector, ParametricRegion, parametric_region_list, ImplicitRegion
  from sympy.vector.operators import _get_coord_systems
label_desc: Use image node_id 3 for calling the ParametricIntegral obj's underlying member method code with example usage: obj.field() and returns: self