f = open('small.txt')
m_list = ''
m_dict = {}
for line in f:
    m_list += line.lower()    
m_list = m_list.replace(' ','\n').split('\n')
m_dict = dict.fromkeys(m_list)
for name in m_dict:
    m_dict[name] = 0
for name in m_list:
        if name in m_dict:
            m_dict[name] += 1
for name in m_dict:
    print(str(name) + ' => ' + str(m_dict[name]))

 m_dict = {}
with  open('small.txt') as file:
   m_list = [i.lower() for i in file.read().split()]
for key in set(m_list):
    m_dict[key] = str(m_list.count(key))
for key,value in m_dict.items():
    print('слов "{}"  в тексте - {} '.format(key,value))

 with  open('small.txt') as file:
   m_list = [i.lower() for i in file.read().split()]
   for key in set(m_list):
       print(key,'=>',m_list.count(key)

 print(m_dict.keys()[:n])

  
>>> d = {1: 2, 3: 4}
>>> d.keys()[:2]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'dict_keys' object is not subscriptable
>>> 

  
>>> d = {1: 2, 3: 4}
>>> list(d)[:2]
[1, 3]
>>>

  
>>> d = {1: 2, 3: 4, 5: 6, 0: 0}
>>> 
>>> sorted(d.items())[:2]
[(0, 0), (1, 2)]
>>>