Я хотел запустил код,а у меня выводит "indention error"

a1=str(input(""))
if a1=="calculator":
    from tkinter import *
    from tkinter import messagebox
    from tkinter import ttk
    import math
    import sys

    root = Tk() 
    root.title("Calculator")

    bttn_list = [
    "7", "8", "9", "+", "*", 
    "4", "5", "6", "-", "/",
    "1", "2", "3",  "=", "xⁿ",
    "0", ".", "±",  "C",
    "Exit", "π", "sin", "cos",
    "(", ")","n!","√2", ]

    r = 1
    c = 0
    for i in bttn_list:
            rel = ""
            cmd=lambda x=i: calc(x)
            ttk.Button(root, text=i, command = cmd, width = 10).grid(row=r, column = c)
            c += 1
        if c > 4:
                    c = 0
                    r += 1
                    calc_entry = Entry(root, width = 33)
                    calc_entry.grid(row=0, column=0,            columnspan=5)

    def calc(key):
         global memory
         if key == "=":
                  str1 = "-+0123456789.*/)(" 
                     if calc_entry.get()[0] not in str1:
                    calc_entry.insert(END, "First symbol is not number!")
                    messagebox.showerror("Error!", "You did not enter the number!")
                try:
                    result = eval(calc_entry.get())
                        calc_entry.insert(END, "=" + str(result))
                    except:
                    calc_entry.insert(END, "Error!")
                 messagebox.showerror("Error!", "Check the correctness of data")
            
         elif key == "C":
                calc_entry.delete(0, END)
        
        elif key == "+":
                if "=" in calc_entry.get():
                calc_entry.delete(0, END)
            try:
                 if calc_entry.get()[0] == "-":
                        calc_entry.delete(0

Ошибка:

  File "file.py", line 37
    if calc_entry.get()[0] not in str1:
                                      ^
IndentationError: unindent does not match any outer indentation level