code: def l2_norm(f, lim):
      """
      Calculates L2 norm of the function "f", over the domain lim=(x, a, b).
  
      x ...... the independent variable in f over which to integrate
      a, b ... the limits of the interval
  
      Examples
      ========
  
      >>> from sympy import Symbol
      >>> from gibbs_phenomenon import l2_norm
      >>> x = Symbol('x', real=True)
      >>> l2_norm(1, (x, -1, 1))
      sqrt(2)
      >>> l2_norm(x, (x, -1, 1))
      sqrt(6)/3
  
      """
      return sqrt(integrate(Abs(f) ** 2, lim))
  
file_path: sympy/examples/advanced/gibbs_phenomenon.py
imports: from sympy import var, sqrt, integrate, conjugate, seterr, Abs, pprint, I, pi, sin, cos, sign, lambdify, Integral, S
label_desc: Use image node_id 1 for calling a global function with example usage: l2_norm(f, lim) and returns: sqrt