code: def ncdf(ctx, x, mu=0, sigma=1):
      a = (x - mu) / (sigma * ctx.sqrt(2))
      if a < 0:
          return ctx.erfc(-a) / 2
      else:
          return (1 + ctx.erf(a)) / 2
  
imports: from .functions import defun, defun_wrapped
label_desc: Use image node_id 9 for calling a global function with example usage: ncdf(ctx, x, mu, sigma) and returns: unknown, unknown