private bool IsAssignableToCore(UndeclaredStructType self, IType type)
 {
     return(type is UndeclaredStructType undeclaredType && undeclaredType.Name == self.Name);
 }
 private bool IsAssignableToWithSubstitutionsCore(UndeclaredStructType self, IType type, ICollection <Substitution> substitutions)
 {
     return(type is UndeclaredStructType undeclaredType && undeclaredType.Name == self.Name);
 }