class Taxpayer:
  income = 0
  def __init__(self,income):
   self.income = income
   self.validateIncome()
  
  def validateIncome(self):
    if self.income.isnumeric() == False:
      raise valueError("The income {} is not numeric" . format(self.income))
      
  def calculate_tax(self):
    return float(self.income)* 0.3
    
income = input("What is your income")
employee = Taxpayer(income)
print(employee.calculate_tax())