class_docstr: Chebyshev polynomial models and functions,
  including specific methods for Tn(z) n=2,4,6,8,16, Equation (27-33) of [2]
  
  NOTE: default is T8(z)
docstr: forward Chebyshev function
docstr_tok: ["forward","Chebyshev","function"]
code: def forward(self, x):
      """forward Chebyshev function"""  # of order %s""" % (len(self.coeffs)-1)
      fwd = Polynomial.ForwardFactory(self, self.coeffs)
      return fwd(x)
  
imports: from .abstract_model import AbstractModel
  from numpy import sum
  from numpy import asarray
  from mystic.math import polyeval, poly1d
  from mystic.models._model_helper import chebyshev2coeffs, chebyshev4coeffs, chebyshev6coeffs, chebyshev8coeffs, chebyshev16coeffs
label_desc: Use image node_id 3 for calling the Chebyshev obj's underlying member method code with example usage: obj.forward(x) and returns: fwd