code: def npdf(ctx, x, mu=0, sigma=1):
      sigma = ctx.convert(sigma)
      return ctx.exp(-((x - mu) ** 2) / (2 * sigma**2)) / (
          sigma * ctx.sqrt(2 * ctx.pi)
      )
  
imports: from .functions import defun, defun_wrapped
label_desc: Use image node_id 8 for calling a global function with example usage: npdf(ctx, x, mu, sigma) and returns: unknown