Need help with extracting the exons, the joined exons should come out as shown

FASTA files to record the DNA sequences (NBPF1.fasta) >hg38_knownGene uc001ayw.5 range-chr1:16563943-16592021 5'pad 0 3'pad 0 strands. repeatMasking-none ATGGTGGTATCAGCTGGCCCTTGGTCCAGCGAGAAGGCAGAGACGAACAT TTTAGAAATCAACGAGAAATTGCGCCCCCAGCTGGCAGAGAACAAACAGC AGTTCAGAAACCTCAAAGAGAAATGTTTTGTAACTCAACTGGCCGGCTTC CTGGCCAACCGACAGAAGAAATACAgtaagatctataggctcaccatcat gaaagtgatgaatgatgtcctgtcttctctctgagacactaaatgctctc tccatcaaaaataatttcatccttcctgtacttctaggaaaacagaaatg ggtattttaacattttgttaaagttggaagacagaggtaccaaagtattt agcaactttccatgtttgcaatcaggtgggggtgggactagagttaaact Read FASTA files In [3]: dna_file open("NBPF1.fasta") my-dna = dna-file. read() print (my_dna[0:10]) >hg38_know Exercise Extract multiple exons from the fasta file (NBPF1.fasta) Exon1: Exon2: Exon3: Join all the exons into a single sequences In [4]: joined_exons".join(c for c in my_dna if c.isupper()) print (joined_exons [1:300]) TGGTGGTATCAGCTGGCCCTTGGTCCAGCGAGAAGGCAGAGACGAACATTTTAGAAATCAACGAGAAATTGCG CCCCCAGCTGGCAGAGAACAAACAGCAGTTCAGAAACCTCAAAGAGAAATGTTTTGTAACTCAACTGGCCGGC TTCCTGGCCAACCGACAGAAGAAATACAAGTATGAAGAGTGTAAAGACCTCATAAAATTTATGCTGAGGAATG AGCGACAGTTCAAGGAGGAGAAGCTTGCAGAGCAGCTCAAGCAAGCTGAGGAGCTCAGGCAATATAAAGTCCT GGTTCAG FASTA files to record the DNA sequences (NBPF1.fasta) >hg38_knownGene uc001ayw.5 range-chr1:16563943-16592021 5'pad 0 3'pad 0 strands. repeatMasking-none ATGGTGGTATCAGCTGGCCCTTGGTCCAGCGAGAAGGCAGAGACGAACAT TTTAGAAATCAACGAGAAATTGCGCCCCCAGCTGGCAGAGAACAAACAGC AGTTCAGAAACCTCAAAGAGAAATGTTTTGTAACTCAACTGGCCGGCTTC CTGGCCAACCGACAGAAGAAATACAgtaagatctataggctcaccatcat gaaagtgatgaatgatgtcctgtcttctctctgagacactaaatgctctc tccatcaaaaataatttcatccttcctgtacttctaggaaaacagaaatg ggtattttaacattttgttaaagttggaagacagaggtaccaaagtattt agcaactttccatgtttgcaatcaggtgggggtgggactagagttaaact Read FASTA files In [3]: dna_file open("NBPF1.fasta") my-dna = dna-file. read() print (my_dna[0:10]) >hg38_know Exercise Extract multiple exons from the fasta file (NBPF1.fasta) Exon1: Exon2: Exon3: Join all the exons into a single sequences In [4]: joined_exons".join(c for c in my_dna if c.isupper()) print (joined_exons [1:300]) TGGTGGTATCAGCTGGCCCTTGGTCCAGCGAGAAGGCAGAGACGAACATTTTAGAAATCAACGAGAAATTGCG CCCCCAGCTGGCAGAGAACAAACAGCAGTTCAGAAACCTCAAAGAGAAATGTTTTGTAACTCAACTGGCCGGC TTCCTGGCCAACCGACAGAAGAAATACAAGTATGAAGAGTGTAAAGACCTCATAAAATTTATGCTGAGGAATG AGCGACAGTTCAAGGAGGAGAAGCTTGCAGAGCAGCTCAAGCAAGCTGAGGAGCTCAGGCAATATAAAGTCCT GGTTCAG