phone screen:
import json
docid_to_title = json.loads('{"28099931907": {"content": {"title": "Zika dollars and Internet fight in play as government shutdown looms"}}, "28108959337": {"content": {"title": "Leaders express renewed optimism about flood relief as Congress aims to avoid a government shutdown"}}, "28110814722": {"content": {"title": "Senate passes stopgap spending bill, $1.1B to fight Zika"}}, "28101422554": {"content": {"title": "Senate blocks bill to avert shutdown as De..."}}, "28099132063": {"content": {"title": "Senate Dems threaten shutdown over Flint aid"}}, "28101167069": {"content": {"title": "Zika dollars, internet fight in play as government shutdown looms"}}, "28102817621": {"content": {"title": "House leaders reach deal on Flint aid, potentially averting shutdown"}}, "28108039075": {"content": {"title": "Deal reached to keep US government running, help Flint"}}, "28098698025": {"content": {"title": "Defeat of Republicans\\u2019 stop-gap spending bill brings federal government closer to a shutdown"}}, "28097027782": {"content": {"title": "Will Democrats force a government shutdown over Flint relief funds?"}}, "28111131355": {"content": {"title": "Lawmakers strike deal to avoid shutdown"}}, "28110856451": {"content": {"title": "Louisiana flood aid, $500 million, survives Senate budget fight"}}, "28106625838": {"content": {"title": "Pelosi aide says deal with Speaker Ryan covers Flint aid"}}, "28099931906": {"content": {"title": "Zika dollars and Internet fight in play as government shutdown looms"}}, "28096859458": {"content": {"title": "Are Democrats pushing the federal government toward a shutdown?"}}, "28110814723": {"content": {"title": "Senate passes stopgap spending bill, $1.1B to fight Zika"}}, "28093906031": {"content": {"title": "will democrats force a federal shutdown over Flint relief funds?"}}, "28108873175": {"content": {"title": "Senate Democrats accept deal on Flint aid, potentially averting shutdown", "sources": ["ABC", "FOX"]}}, "28103573587": {"content": {"title": "ALEXANDER : Senate Democrats\\u2019 Election Politics Are Putting Babies at Risk"}}, "28096849799": {"content": {"title": "Democrats poised to block stopgap funding bill over Flint"}}, "28098943696": {"content": {"title": "Senate blocks stopgap bill to prevent shutdown this weekend"}}, "28110942840": {"content": {"title": "Senate Passes Short-Term Government Funding Measure"}}, "28107038234": {"content": {"title": "House aides: Deal reached to help Flint, keep US gov\'t open"}}, "28084509076": {"content": {"title": "Week ahead: Spending fight shifts from Zika to Flint"}}, "28089633072": {"content": {"title": "Flint water aid spending bill\'s sticking point"}}, "28099749478": {"content": {"title": "Government shutdown looms due to partisan clash over Flint aid"}}, "28099468922": {"content": {"title": "Funding bill rejected as shutdown nears"}}, "28107540657": {"content": null}, "28098940419": {"content": {"title": ""}}, "28110838282": {"content": {"title": "Senate approves deal to keep government open, combat Zika"}}, "28093943889": {"content": {"title": "Democrats press talks as showdown vote looms on funding bill"}}, "28099506681": {"content": {"title": "Republicans ready new bid to avoid shutdown"}}, "28084188573": {"content": {"title": "Zika: Congressional showdown coming this week"}}, "28109130960": {"content": {"title": "McConnell: Let\\u2019s Keep Working Together to Pass Critical Resources"}}, "28097129455": {"content": {"title": "McConnell: We Cannot Afford to Wait Any Longer on Providing Critical Resources"}}, "28110653655": {"content": {"title": "Deal averts federal shutdown, ignores Cruz\' Internet \'giveaway\'"}}, "28110819318": {"content": {"title": "Senate passes spending bill after separate Flint aid deal"}}, "28106754872": {"content": {"title": "Democrats: Deal reached to help Flint, keep US gov\'t open"}}, "28093906030": {"content": {"title": "Will Democrats force a federal shutdown over Flint relief funds?"}}, "28108257314": {"content": {"title": "US Senate Again Blocks Bill That Includes Zika Funding"}}, "28097690131": {"content": {"title": "Cornyn: Democrats Pushing Country Towards Shutdown for Political Gain"}},...)
# 1. Write a function that identifies all the unique words across all the `content.title` fields in `docid_to_title`.
# 2. Write a function that computes the k most frequent bigrams across all the `content.title` fields in `docid_to_title`.
# 3. Find all the duplicate titles in `content.title` fields in `docid_to_title`.