Замена значения в файле

d = {}
with open('print.txt') as f:
      for line in f:
          key, value = line.split('=')
          d[key.replace(' ', '')] = float(value.replace('\n',''))
 
d['y'] = float(input('Input Y: '))
 
with open('print.txt', 'w') as f:
    for key, value in d.items():
        f.write('%s = %s\n' % (key, value)
 
print('Done')

key, value = line.split('=')

line = line.split('=')
if len(line) != 2:
    print('Error split in: <<%s>>' % line)
    continue
key, value = line

x = float(input('y = '))
 
f = open('print.txt')
data = f.readlines()
f.close()
varianti = ['Y=','Y = ','Y =''y=','y = ','y =']
tmp = None
for i in range(len(data)):
    for s in range(len(varianti)):
        if varianti[s] in data[i]:
            data[i] = varianti[s] + str(x) + '\n'
            break
            
f = open('print.txt', 'w')
f.writelines(data)
f.close()

x = float(input('y = '))
 
f = open('print.txt')
data = f.readlines()
f.close()
data_1 = []
for i in range(len(data)):
    data_1.append(data[i])
    data_1[i] = (data_1[i].lower()).replace(' ','')
    if 'y=' in data_1[i]:
        data[i] = data[i][:(data[i].find('='))+1]+ ' ' + str(x) + '\n'
    
f = open('print.txt', 'w')
f.writelines(data)
f.close()