from Bio import SeqIO

def load_genome(genome_id):

    # Load the extraterrestrial genome sequence from a specified database

    # and return the DNA sequence

    # Replace 'database' with the actual database name or API call

    genome_sequence = 'database.get_sequence(genome_id)'

    return genome_sequence

def edit_genome(genome_sequence, target_gene_sequence, modification):

    # Perform targeted gene editing using the CRISPR-Cas9 system

    # Replace the following code with the actual CRISPR-Cas9 implementation

    edited_sequence = genome_sequence.replace(target_gene_sequence, modification)

    return edited_sequence

# Example usage

genome_id = 'ET123'

target_gene_sequence = 'ATGCTGACGT'

modification = 'ATGCTGCCGT'

genome_sequence = load_genome(genome_id)

edited_sequence = edit_genome(genome_sequence, target_gene_sequence, modification)

# Output the modified genome sequence in a markdown code block

print(f"```\n{edited_sequence}\n```")