import symfit.core.operators

# Expose useful objects.
from symfit.core.fit import (
    Fit, Model, Constraint, ODEModel, ModelError, CallableModel,
    CallableNumericalModel
)
from symfit.core.fit_results import FitResults
from symfit.core.argument import Variable, Parameter
from symfit.core.support import variables, parameters, D

# Expose the sympy API
from sympy import *
import symfit.core.operators

# Expose useful objects.
from symfit.core.fit import (
    Fit, Model, Constraint, ODEModel, ModelError, CallableModel,
    CallableNumericalModel, GradientModel
)
from symfit.core.fit_results import FitResults
from symfit.core.argument import Variable, Parameter
from symfit.core.support import variables, parameters, D

# Expose the sympy API
from sympy import *
Add GradientModel to the API
Add GradientModel to the API

  import symfit.core.operators
  
  # Expose useful objects.
  from symfit.core.fit import (
      Fit, Model, Constraint, ODEModel, ModelError, CallableModel,
-     CallableNumericalModel
+     CallableNumericalModel, GradientModel
  )
  from symfit.core.fit_results import FitResults
  from symfit.core.argument import Variable, Parameter
  from symfit.core.support import variables, parameters, D
  
  # Expose the sympy API
  from sympy import *
Add GradientModel to the API
## Code Before:
import symfit.core.operators

# Expose useful objects.
from symfit.core.fit import (
    Fit, Model, Constraint, ODEModel, ModelError, CallableModel,
    CallableNumericalModel
)
from symfit.core.fit_results import FitResults
from symfit.core.argument import Variable, Parameter
from symfit.core.support import variables, parameters, D

# Expose the sympy API
from sympy import *
## Instruction:
Add GradientModel to the API
## Code After:
import symfit.core.operators

# Expose useful objects.
from symfit.core.fit import (
    Fit, Model, Constraint, ODEModel, ModelError, CallableModel,
    CallableNumericalModel, GradientModel
)
from symfit.core.fit_results import FitResults
from symfit.core.argument import Variable, Parameter
from symfit.core.support import variables, parameters, D

# Expose the sympy API
from sympy import *