nltk PunktSentenceTokenizer: tokenize sentences without whitespace in between

Question

Is it possible to make the NLTK PunktSentenceTokenizer to split sentences that do not have whitespace between each other?

from nltk.tokenize.punkt import PunktSentenceTokenizer

sent_tokenizer = PunktSentenceTokenizer()
print(sent_tokenizer.tokenize('Sky is blue.Metal is black.'))

'''
Output:

['Sky is blue.Metal is black.']
'''